NZ 9421 then OZ 9521 at San Francisco
Seattle → San Francisco → Houston
Timetable, San Francisco time
21:50NZ 9421 from Seattle at the gate
16:40OZ 9521 to Houston leaves the gate
18 h 50 apart on the timetable, overnight
OZ 9521 leaves 18 h 50 after NZ 9421 arrives on the timetable: more than half a day, so not a connection we count.